Browse Prior Art Database

Use of Validating Data to Ensure Data Integrity in Caching Array Controllers

IP.com Disclosure Number: IPCOM000015552D
Original Publication Date: 2002-Sep-01
Included in the Prior Art Database: 2003-Jun-20
Document File: 2 page(s) / 74K

Publishing Venue

IBM

Abstract

Introduction: In RAID controllers the goal is to minimize the customers exposure to data loss due to any components failure. To protect against disk failures, parity striping (RAID 5) and mirroring (RAID 1) are performed on the users data. To protect against controller failures, i.e. firmware errors or hardware problems, redundant controllers are used. These are actions taken to protect a users data in the event a single component failure takes place. The problem is that while a system is in a degraded mode, a second component failure can cause user data loss. This disclosure provides a method to help limit the customers exposure to data loss due to multiple disk failures.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 52% of the total text.

Page 1 of 2

Use of Validating Data to Ensure Data Integrity in Caching Array Controllers

Introduction: In RAID controllers the goal is to minimize the customers exposure to data loss due to any components failure. To protect against disk failures, parity striping (RAID 5) and mirroring (RAID 1) are performed on the users data. To protect against controller failures, i.e. firmware errors or hardware problems, redundant controllers are used. These are actions taken to protect a users data in the event a single component failure takes place. The problem is that while a system is in a degraded mode, a second component failure can cause user data loss. This disclosure provides a method to help limit the customers exposure to data loss due to multiple disk failures.

Problem Description: In today's RAID controllers when a disk fails, a rebuild is started to recreate the data that was written to the failed disk. When the rebuild completes the RAID group is then fully redundant and can once again withstand a single disk failure. The goal of this disclosure is to limit the time between when the data on the spare drive is fully regenerated and when the failure takes place. To accomplish this, the firmware takes advantage of information received from the drive, for example, the number of sectors which have needed to be reassigned, or the drives predicted fault information. With this information the firmware can make a determination that a drive is likely to suffer a hard failure in the near future. The goal is to have the data on that drive copied onto a spare drive prior to the failure actually taking place. In this case, if the drive actually fails, the controller will not need to perform the rebuild and there is no exposure to a second drive failure.

Problem Solution: When a driv...